Yes, I am using 4.2.1 GA. The exception I'm getting is posted here: http://www.jboss.com/index.html?module=bb&op=viewtopic&t=117754 The class that is not being found is passed as a parameter to a session bean (stateless, remote). Note that even when I changed myClass[] for Object[] I get the same exception (it'd read java.lang.ClassNotFoundException: No ClassLoaders found for: java.lang.Object[]). Then I changed that parameter to Vector, and I did not get the error any more. Still, it'd no deploy well. I got another error about a class cast exception for the context... This is all very odd because the exact same application would deploy perfectly well (and pass a massive amount of junit tests), as long as it was ALL EJB 2.1. As soon as a single @Stateless annotation was introduced, the exceptions started. Thanks for any help. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4080925#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...